1. Field of the Invention
The present invention relates in general to a tableware washer for automatically washing tableware and, more particularly, to a water spraying device for the tableware washer having a rotatable water spraying arm.
2. Description of the Prior Art
Tableware washers are used for automatically washing tableware stained with food remnants. As well known to those skilled in the art, a tableware washer should be provided with means for spraying water upon tableware laid on a rack of the washer.
With reference to FIGS. 1 and 2, there is shown a conventional tableware washer in a partially broken view and a water spraying device of the washer in a partially sectional view respectively. The water spraying device comprises a spraying arm 6 and a spraying arm rotating mechanism. In order to not only support the spraying arm 6 and the arm rotating mechanism but also guide water to the arm 6, the device further includes a frame 1 comprising an upper frame 1a and a lower frame 1b. Here, the upper frame 1a is rotatable with respect to the lower frame 1b and rotatably receives the spraying arm 6 at its upper section such that the arm 6 diametrically extends outward. A ring gear 4 having teeth on its annular top surface is mounted on the top of the lower frame 1b.
At the outside of the upper frame 1a, a spur gear 5 gears into the ring gear 4. This spur gear 5 is rotatably mounted on the side wall of the upper frame 1a such that its rotating shaft 3 is vertically mounted on the side wall of the frame 1a. The rotatable spur gear 5 is connected to the spraying arm 6 by a connecting rod 7, to cause the spring arm 6 to rotate back and forth in opposite directions as the spur gear 5 rotates about the ring gear 4. This connecting rod 7 is hinged to both a portion of the spur gear 5, the portion being spaced apart from the rotating shaft 3 by a distance l, and an outer surface of the spraying arm 6.
In operation of the washer, a power switch of the washer is switched on under the condition that the tableware stained with food remnants is laid on a rack 9 inside a washer housing 8, a drive motor 10 starts and generates a pumping force for supplying the water under a given pressure to the spraying arm 6 through a water passage 2 in the upper frame 1a. At this time, opposed ends of the spraying arm 6 are provided with eccentric holes, so that there is generated a rotating force in both the arm 6 and the upper frame 1a when the pressurized water is ejected from the eccentric holes. Hence, the arm 6 and the upper frame 1a are turned in one direction about the lower frame 1b.
The spur gear 5 of the upper frame la gearing into the ring gear 4 is thus rotated about its shaft 3 and moves along the ring gear 4. As a result of rotation of the spur gear 5, the spraying arm 6 rotatably received in the upper frame 1a and hinged to the connecting rod 7 is alternately rotated in opposed directions at a rotating angle determined by the distance l between the eccentric hinged portion and the rotating shaft 3 of the spur gear 5. Therefore, the spraying arm 6 rotated in opposed directions sprays the water under pressure upon the tableware laid on the rack 9.
However, it has been noted that the above water spraying device has the following problems.
First, since the device has many elements, that is, the upper and lower frames 1a and 1b, two gears 4 and 5 and a connecting rod 7 hinged to both the arm 6 and the spur gear 5, its construction is very complex and inevitably deteriorates productivity of the tableware washer.
Second, the power transmission for rotating the spraying arm 6 is carried out by the gears 4 and 5, so that there is generated considerable noise in operation of the device.
Third, the arm rotating mechanism is only provided at one side of the spraying arm 6 even though this spraying arm 6 comprises two arm sections oppositely extending from the upper frame 1a, so that a stable and smooth rotation of the arm 6 cannot be achieved.